Drafting machine



Se t. 23, 1952 A. 1.. BAKER' DRAFTING MACHINE 3 Sheets-Sheet 1 Filed Feb. 6, 1948 INVENTOR. ALLISTER L. BAKER R m 8 t B t s e N 1 m mL 1 S N a 1R 2 a E e h S L 3 w Gm m k E m m M n. B G \m A L m m A m M D v \M ow N 0 Sept. 23, 1952 Flled Feb 6, 1948 Sept. 23, 1952 A. L. BAKER DRAFTING MACHINE 3 Sheets-Sheet 3 Filed Feb. 6, 194

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ALLISTER l BAKER Patented Sept. 23, 1952 DRAFTING MACHINE Allister L. Baker, Jersey City, N. J assignor to Keufiel & Esser Company, Hoboken, N. .L, a corporation of New Jersey ApplicationFebruary s, 194s,- Serial No. 6,789

19 Claims.

This invention relates to protractor or drafting heads on drafting machines. Various forms of drafting machines are well known in the art,

7 such as, the pulley and band type, in connection with which this invention .isparticularly useful. The usual type comprises a fixed member clamped. to a drawing board, a first movable arm pivoted at one end to the fixed. member, a secondmovable arm pivoted at one end to the moving end of the first arm, and a drafting head carried at the free end of the second movable arm and movable over thedrawing board. The drafting head includes a protractor and a protractor arm with means for holding one or more scales, rulers, or straight edges, which can be rotatedabout the protractor. As the drafting head'is moved over the drawing board, orientation of some member of the protractor or drafting head. is held constant by a combination of pulleys and bands, parallelograms or the like. The present invention relates only to the drafting head and it should be understood that the form of the other parts of themachine in no way affects the invention.

Specifically, theinvention relates to an improved type of drafting head which may be combined in any suitable manner, known in the art,

with other parts necessary to form a drafting machine.

One object of the invention is to provide in a drafting head means for making extremely fine adjustments when setting the protractor arm to selected angles orto a selected base line.

Another object of the invention is to provide a vernier or index mark plainly visible at all positions of the protractor arm.

Another object of the inventionis to provide a simple arrangement to permit rotating the circle without rotating the other member of the head.

. A further object of the invention is to provide a fully covered and protected protractor scale.

These and other objects of the invention and the means for their attainment will be more ap- I in the direction of the arrows.

Figure IV is a view in sectional elevation taken along the line IVIV in Figures I and II looking in the direction of the arrows but showing the magnifying lens rotated from its position in Figure II.

In Figure I, the fixed member or anchor 2 is provided with means for clamping it to the drawing board. The first movable arm 4 is pivoted to this member 2 at one end and to the second movable arm 6 at its other end. The drafting head 8 is at the free end of the second movable arm 8.

As shown in Figure IV, the band l2 passes around the drafting head pulley I'll. A ball bearin I 4 provides frictionless rotation means between the drafting head pulley and the head bracket 1 of the second movable arm B, so that the arm may rotate with respect to the pulley which is held in orientation by the band 12. The inner race of the ball bearing I4 is held onto the sleeve I l of the drafting head pulley 0 as by the nut It. The outer race is attached to the head bracket 1 in this embodiment by a press fit.

The center stud or pivot pin I8 is free to turn inside the drafting head pulley l0 and is accurately centered therewith being in close bearing contact with an internal bearing surface of the sleeve ll of the drafting head pulley Ill. The lower end of the center stud I8 has three portions 20, 22, and 24 of different outside diameter. The limb plate 28 with a protractor scale 92 fits over the portion 22 of center stud i8 and is held in frictional contact against the lower surface of the portion 20 by the spring washer 30. The protractor arm 26 fits over the portion 24 of center stud l8 and is fastened to the portion 22 as by the screws 23. The spring washer 3!! acts between the upper surface of the protractor arm 26 and the lower surface of the limb plate 28. The protractor arm 26 may be provided with chucks or other means to receive one or more rulers, scales. or straight edges 21. The tangent screw arm 32 also fits over the portion 24 and is separated from the protractor arm by the washer 34. The center screw 36 engages threads in the portion 24 to hold the tangent screw arm 32 on the stud in such a manner that it is free to rotate about the stud. The center screw 36 may also act as a glider on which the drafting head rests as it is moved over the drawing board; or special studs 31 may be provided for this purpose.

The upper end of the center stud I8 is provided with a portion 38 of smaller outside diameter and a threaded portion 40 of still smaller outside .held rigidly thereto as by the screw 58.

A magnifying lens 52 is held by themagnifying lens arm 54 which is provided'with a hole fitting over the outside diameter of the sleeve H which is an integral part of the drafting head pulley Ill. The magnifying lens arm 54 is held in place on the sleeve II by means of the retaining ring 56. The action of the retaining ring 55 is such that the magnifyin 1ens arm 54 remains oriented with the drafting head pulley l and remains over the index mark or Vernier 94 in normal use I of the drafting machine. The magnifying lens arm 54 may be turned by hand about'the sleeve H if it is desired to change it from a reading to 'a. non reading position, p

g The annular cover plate 58 moves with. the drafting head pulley Hi to which it may be fastened directly or through the ring '5! as by screws 60 and 64. The annular cover plate dais. prefer- 1 ably of a transparent non-fragile material such as a plastic but it may alsobe constructed of, an opaque material having a cut out or transparent portion at the position of the Vernier. The: an-

nular Vernier plate 6.2 is fastened to and held in.

orientation by the, drafting head pulley; conveniently through the cover plate holding ring 51 by the screws 64,

As has already been: described the limb plate 28 is held infrictional engagement Withthe pro-' tractor arm as and the; center-stud is, by the spring washer 3.0, so that the protractor in normal, use turns with the center stud. E8, the knob 48;, andthe protractor arm 26. v

The protractor holding plate 55 is, fastened to the limb plate 28 by means of the ring; 68. and screws 10..

The pin 72, the lever arm 14 and the spring washer 16 comprise a pin clamp for fixing the protractor holding plate 66 and thereby the limb'plate 23 with its protractor scale 92 to the drafting head pull y. Theupper party of the pin 12, is slidably mounted in a, hole in the draftin head pulley 10. The lowerpart of the pin 12. is threaded to fit afemale, thread in the lever arm .14. The lower end of the pin 12 is of hexagonal section and passesv through a hexagonal hole in the cover plate holding ring 51; The. spring Washer 16. acts between the drafting head pulley vclamps it'thereto. v

The pressure, applied: against the. protractor holding plate 66, by the pin 12 is limited to that obtainable from the spring washer, 1.6. When the pinclamp. is clo as, described. the limb plate .28 and. the. pr traetorez are.v held in. orientation by. the draftingheadplllley. The protractorar'm' 26 may then be turned aboutthe center. stud [8 .without moving the protractor 92.

. In Fi ures II; III, IV, he. tangent screw 18.

clamp screw 80, looking lever. 8.2. tension spring 4 84, and other minor parts to be described form a. clamp and tangent screw arrangement for fine adjustment of the protractor arm 26 or thereby the protractor 92. The locking lever 82 is provided with a female thread which engages with the clamp screw so that when the locking lever 82 is pushed in one direction it pulls the clamp screw 89 downward;- against theannular cover plate '58, clampingfit betwee'n the clamp screw '80 and the bracket 86 which is an integral part of the tangent screw arm 32. The clamp screw 80 is pinned to the bracket 86 by the set screw 88 to prevent its turning when the locking lever 82 isactuatedi :The head of the clamp screw v38 is. provided-with several holes spaced equally in a'circle. Theset screw 83 will fit each of these holes sothat in the event that the clamping action becomeslose it may be tightened by turning the clamp screw 80 to tighten it and using the set screw 88 in another hole.

The female threaded member?!) (see EigureIlI) is carried h elbrecke't '86 f t ta eents rsw arm 32. The tangent screw 18 operatesin the female threadedmember 90' against the-projection ill at the edge of the protractor arm 26.' The point of the tangent screw is held in contact with the projection so of the protractor arm 26 by the tension spring .84 acting between the tangent screw arm 32 and the screw 25 onprotractorjarm 26. When the clamp is closed, bythe lockinglever 82, the tangent, screw gives a fineadjustment to the protractor arm either for adjusting the protractor arm 25 or the protractor 92 relative to the drafting-head pulley] The tension spring 84 holds the tangent screw} arm 32 am ne protractor arm 26 'toge'thersdthat theyact as one to give a. fine adjustment 1 The tension spring 84 is so positionedjjthat it cannot be extended whendrawing lines due to pressure'exerted against the'straightedge 21 by the drawing instrument. Such pressure will only increase the pressure between'the point-of the tangent screw '18 and the projection 91 of the protractor arm 26''. When the locking lever '82jis clo's'ed- 'it' locks the tangent screwarm 32','byine'ans of the bracket 86, to the annular cover plate 58. Since the annular cover plate is fastened to the drafting" head pulley ID, the effect 'of the clamping action; is to lock the tangent screw arm 32 and thereby the protractor arm 26 to the drafting head pulley" Ill.

The limb'plate' Z-B'is provided on ftsupp'er surface with a protractor scale 92 extending through the full 360"; The annular Vernier plate 62 is provided on its upper surface with air-index mark or preferably a vernier-scale 94, one of the lines of which may be eonsideresan indeii mark lining up with the protractor scale 92. The divisions of the protractorfand vernier .sc alesare chosen toread angles to any desired accuracy consistent with the inherent accuracy oflthe parts of the machine. In the preferred embodiment of the invention the protractorscale is divided to divisions representing 30 minutes and 'nier scales 94. Since the vernier scale does not move with the protractor arm it is not necessary for the operator to move his head when finding the angle. The arm may be set more accurately to the desired angle, by clamping the tangent screw arm 32 to the drafting head pulley ID with the locking lever 82 and making a fine adjustment of the protractor arm carrying the protractor 92 by means of the tangent screw 18. Having thus set the protractor arm to the desired angle, the drafting head 8 may bemoved over the drawing board; The combination of bands and pulleys maintain the orientation or angle of the scale or straightedge 2'! on the protractor arm 26. When -a straight edge attached to the protractor arm passesthrough a desired point, the line is drawn at the selected angle through this point. By moving the drafting head again lines may be drawn through any other desired points at the same selected angle. Lines may be so drawn through any desired points at any other desired angle to the same base line by resetting the protractor arm in the manner described.

If it isdesired to change to another base or reference line and make the zero setting of the protractor correspond to this line on the drafting board, this may be accomplished as follows. With both clamps T4 and 82 open, the protractor arm is rotated until the protractor reading on the Vernier 94 is close to zero. Then the locking lever 82 is pushed back to clamp the tangent screw arm 32 to the drafting head pulley ID so that the protractor arm carrying the protractor may be adjusted to make the reading of the protractor and Vernier scales exactly zero.

If this procedure is inconvenient, the locking lever 82 may be closed first to clamp the tangent screw arm 32 to the drafting head pulley l0, and the limb plate 28 may be turned by using the fingers under the drafting head in order to make the protractor scale 92 read close to zero on the Vernier 94. The final adjustment may then be made with the tangent screw as before.

The pin clamp is then closed by means of the lever arm 14. This fixes the limb plate 28 to the drafting head pulley ID maintaining the zero setting of the protractor 92 to the Vernier 94. The

clamp 82 is opened and the protractor arm 26 is rotated against the action of spring washer 39 and if necessary the drafting head is moved over the drawing board until the straight edge 2'! is parallel to or in coincidence with the desired reference or base line. If the locking lever 82 is again closed to clamp the tangent screw to the drafting head pulley, the protractor arm 26 can be given a fine adjustment by means of the tangent screw 18, to set the straight edge exactly on or parallel to the desired reference line, without disturbing the zero setting of the protractor. The pin clamp is then released by means of the lever arm 14. The protractor then will be moved with the protractor arm 26 because of the frictional engagement with the protractor arm through spring washer30. The clamp 82 is then released and the machine is ready for laying off angles from the new reference or base line as previously described.

The invention has'been described as applied to the art of drafting machines. This art, as is understood, includes not only engineering or architectural drawing and the like but also map- .'.ping or surveying. In the latter fields a drafting machine or angle plotting machine of high accuracy and ease of operation such as described herein is of special value.

' Various modifications will occur to those skilled in the art as to the composition, configuration and disposition of the component element going to make up the invention as a whole, as well as in the selection and combination of component elements to accomplish the results herein taught.

Having thus described the invention what is claimed is:

1. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on the drafting board, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, an annular member also rotatable with respect to said member maintained in orientation, cooperating index mark and protractor scale means carried by said member maintained in orientation and said annular member, said annular member and said protractor arm being in constant frictional engagement with each other, resilient means held by said annular member and said protractor arm under a fixed predetermined unadjustable stress, said resilient means applying constant pressure between said annular member and said protractor arm to produce constant frictional forces therebetween, said frictional forces being of sufficient magnitude so that said annular member will be carried by said protractor arm, means for clamping said annular member to said member maintained in orientation to permit rotation of the protractor arm relative to said annular member against the action of said constant frictional forces, and a clamp acting between said protractor arm and said member maintained in orientation to fix the protractor arm at any selected angle.

2. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on the drafting board, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, a protractor provided with graduations; an annular member carried by said member maintained in orientation and covering said protractor thru which the protractor may be read, and clamp means acting between said protractor arm and said annular member and thereby clamping said protractor arm to said member maintained in orientation to fix the protractor arm at any selected angle.

3. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on the drafting board carrying an index mark, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, a protractor having graduations movable adjacent to said index mark, an annular member carried by said member maintained in orientation and covering said protractor thru which the protractor may be read and clamp means acting between said protractor arm and said annular member and thereby clamping said protractor arm to said member maintained in orientation to fix the protractor arm at any selected angle.

4. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on the drafting board,

* a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, an annular member directly above said protractor arm also rotatable with respect to: said; membermaintained. in orientation carryin a protractor sca1e,;a.nd a friction washer between said protractor armand said annular member to move said annular member withasaid protractor arm.

5. Ina drafting machine for use on a drafting board, a drafting head comprising a member maintained in. orientation on the drafting board carrying an, index mark, a protractor arm for carrying at least one straight. edge rotatable With respect to said member maintained in orientation, an annular memberdirectly above said protractor arm also rotatable withv respect to said, member ,maintainedin orientation. carrying a protractor scalev movable adjacent to said index mark, and

a friction. washer between said. protractor arm and said annular member to. move said. annular 'member with said protractor arm.

. .(i'. In. a drafting machine for use on a drafting board, a drafting head comprising a member maintained in. orientation on the drafting board, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, 2. protractor provided With graduations; said protractor and said protractor arm being in constant frictional engagement with each other, resilient means held by said. protractor and said. protractor arm under a fixed predetermined unadjustable stress, said resilient means applying constant pressure between said Iprotractorand said protractor arm to produce constant frictional forces therebetween, said frictionaliorces being of sufficient magnitude so that said protractor will be carried by said protractor ,arm and means for clamping said protractor to said member maintained in. orientation to permit rotation: of the protractor armprelative to said protractor against. the. action. ofv said constant frictional forces.

7.. In a drafting machine for use on a drafting board, a drafting head comp-rising a member maintained in orientation on the drafting board carrying an index mark, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, at protractor having graduations movable adjacent to said index mark, said protractor and said protractor arm being in constant frictional engagement with each other, resilient means held 7 by said protractor and said protractor arm under having its under surface exposed so that it may beturned by hand. I

8. In a drafting machine for use on a drafting board, a drafting head comp-rising a member maintainedin orientation on said drafting board,

a protractor arm for carrying at least one straight edge rotatable with respect to said member maintainedin orientation, a protractor provided with graduations, saidprotractor and said protractor arm bein in constant frictional engagement with each other, resilient means held by said protractor and said protractor arm under a fixed predetermined unadjustable stress, said resilient means applying constant pressure between said annular of said constant frictional forces, said protractor .member'andsaid protractorarm to producecon- 'stant frictional forces therebetween, said frictional. forces being-of. sufficient magnitude so that said protractor; will. be carried by said protractor arm, means: for clamping said protractor to said membermaintained in orientation to permit rotation of. the protractor arm, relative to the protractor against the action of said constant frictional forces and clamp and fine adjustment means act.- ing. between said protractor arm and said member maintained. in orientation to fix the protractor arm at any selected angle.

.9. In. a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on said drafting board, a protractor arm for carrying at least one straight edge rotatable with respect to said member mamtained in orientation, a protractor provided. with graduations, said protractor and said protractor arm being in constant frictional engagement with each other, resilient means held by said protractor and said protractor arm under a fixed predetermined unadjustable stress, said resilient means applying constant pressure between said annular member and said protractor arm to produce constant frictional forces therebetween, said frictional forces being of suflicient magnitude so that said protractor Will be carried by said protractor arm, means for. clamping said protractor to said member maintained in orientation to permit rotation of the protractor arm relative to the protractor against the action of said constant frictional forces, and a clamp acting between said protractor arm and said member maintained in orientation to fix the, protraotor arm at any selected angle. l 7

10. Ina drafting machine for use, on a drafting board, a drafting head comprising a. member maintained in orientation on said. drafting board carrying an index. mark, a. protractor arm for carrying at least one straight edge rotatable With respect to said member maintained in orientation, a protractor having graduations movable adjacentto said index mark, means applying constant frictional forces between said protractor and said protractor arm, said frictional forces being of sufficient magnitude so that said protractor will be carried by said protractor arm, means for clamping said protractor to said member maintained in orientation to permit rotation of the protractor arm relative to the protractor against the action of said constant frictional, forces, and

- a clamp acting betweensaid protractor arm and said member maintained in orientation to fix the protractor arm at any selected angle, and an annular transparent cover plate carried by said member maintained in orientation covering the surface of said protractor.

11. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on. said drafting board carrying an index mark, a protractor arm for carrying at least one straight edge rotatable With respect to said member maintained in orientation, a protractor having graduations movable adjacent to said. index mark, a knob centrally located above said protractor and fastened to said protractor arm for turning it to any selected angle, and means for frictionally engaging said protractor to move it with said protractor arm, clamp means acting to fix said protractorto said member maintained in orientation, to permit rotation of the protractor arm relative to the protractor againstfriction, and a clamp acting between said protractor arm and said member maintained in 9 rientation to fix the protractor arm at any selected angle,and-an annulartransparent cover plate carried by saidmember maintained in orientation and covering the surface of said protractor.

12. In a drafting machine of the wheel and band type for use on a drafting board, a drafting head comprising a drafting head pulley maintained in orientation on said drafting board carrying an index mark, a protractor arm for carrying at least one straight edge rotatable with respect to said drafting head pulley, a protractor having graduations movable adjacent to said index mark, a knob centrally located above said protractor and fastened to said protractor arm for turning it to any selected angle, and means for frictionally engaging said protractor to move it with said protractor arm, clamp means acting to fix said protractor to said drafting head pulley to permit rotation of the protractor arm relative to the protractor against friction, and a clamp acting between said protractor arm and said drafting head pulley to fix the protractor arm at any selected angle, and an annular cover plate carried by said draftin head pulley and covering the surface of said protractor.

13. In a drafting machine for use on a drafting board, a drafting head comprising at least two fundamental members which may be rotated with respect to each other about the central axis of said drafting head, a flat annular plate attached to the first of said fundamental members, a pin sliding in a hole in the second of said fundamental members keyed thereto and having a threaded portion extending from said hole, a female threaded member provided with a lever arm and engaging the threaded portion of said pin, a flat surface carried by the second fundamental member perpendicular to the axis of said pin and separated therefrom by said flat annular plate, and a spring washer acting between said second fundamental member and said female threaded member.

14. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on said drafting board, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, a protractor, a flat annular plate attached to said protractor, a pin sliding in a hole in said member maintained in orientation keyed thereto and having a threaded portion extending from said hole, a female threaded member provided with a lever arm and engaging the threaded portion of said pin, a flat surface carried by said member maintained in orientation perpendicular to the axis of said pin and separated therefrom by said fiat annular plate, and a spring washer acting between said member maintained in orientation and said female threaded member.

15. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on said drafting board, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, a protractor, means carried with said protractor arm for frictionally engaging said protractor, a flat annular plate attached to said protractor, a pin sliding in a hole in said member maintained in orientation keyed thereto and having threaded portion extending from said hole, a female threaded member provided with a lever arm and engaging the threaded portion of said pin, a fiat surface carried by said member maintained in orientation perpendicular to the axis of said pin and separated therefrom by said flat annular plate, and a spring washer acting between said member maintained in orientation and said female threaded member, said protractor having its under surface exposed so that it may be turned by hand.

' 6. In a drafting machine for use on a drafting board, a drafting head comprising at least two fundamental members and a tangent screw arm all of which may be rotated with respect to each other about the central axis of said drafting head, a spring in tension acting between said tangent screw arm and the first of said fundamental members, a member threaded in a direction tansent to a circle having its center on the central axis of the drafting head carried by said tangent screw arm, means for clamping said tangent screw arm to the second of said fundamental members, and a tangent screw engaging said threaded member and projecting against the first of said fundamental members.

17. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on said drafting board carrying an index mark, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, a protractor provided with graduations, and a tangent screw arm rotatable about the central axis of said drafting head, a spring in tension acting between said tangent screw arm and said protractor arm, a member threaded in a direction tangent to a circle having its center on the central axis of the drafting head carried by said tangent screw arm, means for clamping said tanent screw arm to said member maintained in orientation, and a tangent screw engaging said threaded member and projecting against said protractor arm.

18. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on said drafting board, a protractor arm for carrying at least one straight edge rotatable with respect to said member maintained in orientation, a protractor, a fiat annular plate attached to said protractor, a pin sliding in a hole in said member maintained in orientation keyed thereto and having a threaded portion extending from said hole, a female threaded member provided with a lever arm and engaging the threaded portion Of said pin, a fiat surface carried by said member maintained in orientation perpendicular to the axis of said pin and separated therefrom by said flat annular plate, and a spring washer acting between said member maintained in orientation and said female threaded member, and a tangent screw arm rotatable about the central axis of said drafting head, a spring in tension acting between said tangent screw arm and said protractor arm, a member threaded in a direction tangent to a circle having its center on the central axis of the drafting head carried by said tangent screw arm, means for clamping said tangent screw arm to said member maintained in orientation, and a tangent screw, engaging said threaded member and projecting against said protractor arm.

19. In a drafting machine for use on a drafting board, a drafting head comprising a member maintained in orientation on the drafting board, a protractor arm member for carrying at least one straight edge rotatable with respect to said member maintained in orientation, an annular member also rotatable with respect to said mem amass:

member maintained in orientation and said annular member, said annular member and one of the other members being in constant frictional engagement with each other, resilient means held by said members under a fixed predetermined unadjustable stress, said resilient mean applying constant pressure between said annular member and said one of the other members to produce constant frictional forces therebetween, said frictional forces being of sufiicient magnitude so that said annular member will be carried by said one of the other members with which it is in constant frictional engagement and means for clamping 15 said annular member to the other of said other members to permit rotation of said one of the other members with which said annular member is in constant frictional engagement relative to said annular member.

7 ALLISTER L. BAKER.

REFERENCES CITED The following references are of record in the file ofthis patent: V

UNITED STATES PATENTS Number Number Name Date Little June 27, 1939 Wallace Feb. 5, 1946 FOREIGN PATENTS Country Date Great Britain Dec. 5, 1938 Great Britain Feb. 12, 1940 France Nov. 12. 1938 France Apr. 19, 1943 

